Meniere’s Disease

Definition MENIERE’S DISEASE or SYNDROME (also known as IDIOPATHIC ENDOLYMPHATIC HYDROPS) is an uncommon disorder of inner ear which occurs when the normal fluid and electrolyte balance of the inner ear is disrupted. Endolymphatic hydrops is a swelling of one of the tiny, fluid-filled compartments of the inner ear. In a normal inner ear, the fluid is maintained at a constant volume and contains specific concentrations of sodium, potassium, chloride, and other electrolytes. This fluid bathes the sensory cells of the inner ear and allows them to function normally. With injury or degeneration of the inner ear structures, independent control may be lost, and the volume and concentration of the inner ear fluid fluctuate with changes in the body’s fluid/blood. This fluctuation causes the symptoms of hydrops.

Dilated membranous labyrinth in Meniere's disease (Hydrops) Normal membranous labyrinth

etiology

Swelling of the endolymphatic sac or other tissues in the vestibular system of the inner ear Endolymphatic duct may be obstructed by scar tissue, or by narrow from birth Too much fluid secreted by the stria vascularis

risk factors Middle ear infection Stress Syphilis, HSV, CMV Head injury History of allergies Recent viral infection Smoking Respiratory infection Alcohol use risk factors

Incidence of the Disease Peak onset occurs in the 40 – to 60 year age group Men and women are affected equally Approximately 40 persons per 100,000 are affected. In 75 percent of the cases, Meniere’s disease is confined to one ear, while in the other 35 percent , both ears are involved. The National Institutes of Health also estimates that the amount of new cases of Meniere’s disease is around 38,250 each year. Chart on page three of http://oto.wustl.edu/men/mn1.htm

Pathophysiology Due to the etiological factors Overproduction and defective absorption of endolymph Increases the volume and pressure within the membranous labyrinth leads to misfiring of vestibular nerve Distention will occur Rupture and mixing of endolymph and perilymph fluids Two fluids have different compositions Electrolyte balance disrupts within the labyrinth Symptoms range from mild (last less then 2 hours) diseases progress (hours to days)

Signs and Symptoms Classic triad of symptoms – episodic true vertigo, sensorineural hearing loss, and tinnitus Other symptoms are – Feeling of fullness in ear Nausea, vomiting, dizziness, falls, discomfort Diaphoretic and pale sometimes Vitals – elevated pulse and BP Nystagmus during attacks of vertigo

History collection physical examination Diagnosis History collection physical examination The Romberg test generally shows significant instability and worsening when the eyes are closed. The Weber tuning fork test usually lateralizes away from the affected ear. The Rinnes test usually indicates that air conduction remains better than bone conduction.

Lab studies Imaging Studies Other tests No lab studies are specific for Meniere disease. A CBC, urinalysis can be done to rule out the risk factors If an infectious cause is suspected - blood cultures, urine culture, and a cerebral spinal fluid (CSF) examination. Imaging Studies Magnetic resonance imaging C T scan Other tests Audiometry Transtympanic electrocochleography - specifically detects distortion of the neural membranes of the inner ear. Electronystagmography (ENG)

Management - medical Vestibulosuppressants (eg, meclizine) decrease symptoms, but generally only mask the vertigo Diuretics (eg, hydrochlorothiazide) decrease the fluid pressure load in the inner ear. These medications help prevent attacks but do not help once an acute attack has started. Steroids are helpful in endolymphatic hydrops. This probably reduce endolymphatic pressure. Steroids actually can reverse vertigo, tinnitus, and hearing loss.

Intravenous (IV) or intramuscular (IM) diazepam provides excellent vestibular suppression and antinauseal effects. Aminoglycosides (amikacin) – it will treat extreme menieres disease but its toxic effect result in DANDY SYNDROME – complete loss of inner ear function

Destructive surgical procedures Non Destructive surgical procedures Management - surgical Surgical Care: Surgical procedures are divided into 2 major classifications as follows: Destructive surgical procedures Non Destructive surgical procedures

Destructive surgical procedures Rationale to control vertigo: Endolymphatic hydrops causes fluid pressure accumulation within the inner ear, which causes temporary malfunction and misfiring of the vestibular nerve. These abnormal signals cause vertigo. Destruction of the inner ear and/or the vestibular nerve prevents these abnormal signals. As long as the opposite inner ear and vestibular apparatus function normally, the brain eventually will compensate for the loss of one labyrinth.

Endolymphatic sac decompression or shunt Vestibular nerve section Nondestructive surgical procedures: These are directed toward improving the state of the inner ear. They are less invasive than destructive procedures.: Endolymphatic sac decompression or shunt Vestibular nerve section Labyrinthectomy Chemical labyrinthectomy Most of the surgeries are done followed by craniotomy and mastoidotomy.

Endolymphatic sac decompression and/or shunt The endolymphatic sac procedure decreases endolymph pressure accumulation by removing the petrous bone, which encases the endolymph reservoir. This procedure allows the reservoir sac to expand more freely, thus reducing the pressure. A drain or valve from the endolymphatic space to either the mastoid or subarachnoid space can be inserted as another means of further reducing pressure. Success rates (in terms of controlling vertigo and stabilizing hearing acuity) with this procedure are reported at 60-80%.

Vestibular nerve section For patients with useful hearing in the affected ear, sectioning the diseased vestibular nerve can be the ultimate solution. This anatomical separation allows balance function to be isolated and ablated without affecting hearing function.

Although the hearing and balance functions are housed in one common chamber within the inner ear, their neural connections to the brain separate into distinct nerve bundles as they course through the internal auditory canal.

Labyrinthectomy This management option for Ménière disease has the advantage of a high cure rate (>95%) and is useful in the patient whose hearing on the diseased side has been destroyed already by Ménière disease. Labyrinthectomy involves ablation of the diseased inner ear organs.

This procedure is less complex than vestibular nerve section because labyrinthectomy does not require entry into the cranial cavity. Labyrinthectomy is less invasive than vestibular nerve section.

Chemical labyrinthectomy A chemical labyrinthectomy is also known as transtympanic or intratympanic treatment or gentamicin infusion. This is a destructive procedure used for Ménière’s disease. An antibiotic called gentamicin is introduced into the middle ear and absorbed via the round window. The drug destroys the vestibular hair cells so that they cannot send signals to the brain.

Diet: The goal for Ménière disease is to reduce the total body fluid volume. This, in turn, may reduce the inner ear fluid volume. Since sodium seems to play a major role in fluid retention within the inner ear, avoiding salt (eg, pizza, preserved foods) Consult with a nutritionist to establish a rigid salt-restricted diet (1.5 g sodium per day). Avoiding other trigger substances (eg, caffeine, nicotine, alcohol, high-carbohydrate substances, high- cholesterol/triglyceride foods) also can help.

Exercise is recommended in moderation. Activity: Exercise is recommended in moderation. Because of the unpredictable nature of the disease, balance-intensive, dangerous tasks (eg, especially climbing ladders) should be avoided.